The retreading of tires involves the molding of a new section of tread that has a tread surface and an underside surface opposite from the tread surface. In order to attach the underside surface to the tire carcass that is being reused, the underside surface must be brushed to prepare the surface for attachment. The tread section is provided in the form of a longitudinal strip, and an end of the strip is held while the strip is fed into a brush machine. FIG. 1 shows the underside surface 30 of a tread 12 that is engaged by and is being treated by a brush 14. A roller 70 supports the tread 12 as the tread 12 is being brushed. A tread surface 32 of the tread 12 opposite the underside surface 30 engages the roller 70, and the tread 12 engages surfaces on the brush 14 and roller 70 that are both convex in shape. Tread 12 can have various patterns and in some instances may have large open tread blocks. Upon going through the nip created by the brush 14 and roller 70 in the machine direction 40, the leading edge 72 of the tread block 32 is brushed and the tread block 32 tilts upwards. As the tread block 32 moves past the brush 14, the trailing edge 74 of the tread block 32 is pinched by the brush 14 and the roller 70 and the tread block 32 tilts downward. As the tread block 32 is bending at irregular angles through the pinch point of the brush 14 and roller 70, an irregular contact patch is created on the tread block 32 under the brushing force.
The rigidity difference in the tread 12 between the tread blocks 32 and the grooves 26 of the tread 12 will cause the tread 12 to deform differently under the brushing force and feeding force of the tread 12 past the brush 14. This rigidity difference will also cause irregularities in the process due to the bending of the tread 12 along the roller. Through the various factors, the large open block tread 32 will experience irregular movement when being fed past the brush 14 which will cause irregularity in the brushing of the tread 12.
With reference to FIG. 2, the underside surface 30 of the tread 12 is shown after being brushed by the brush 14. Due to the irregular movement via the factors discussed above, the leading edges 72 of the tread blocks 32 will have over brushed areas that can include dig in notches 76 formed by the brush 36 on the underside surface 26. The trailing edges 108 of the tread blocks 54 will have various under brushed spots 78. These under brushed spots 78 must be manually reworked, which is ergonomically unfriendly, and results in additional labor and costs.
A structure with the exact same shape and size as the grooves 26 can be used to restrict the movement of the tread 12 when being brushed. Here, the structure can be formed from a mold of the tread 12 so that it exactly matches the grooves 26 and fills all of the grooves 26 and is located inside of the grooves 26 when the underside surface 30 is being brushed to completely fill up the grooves 26. The structure will support the tread 12 during brushing in order to prevent the tread 12 from moving around and causing irregularities in the brushing process. However, this method requires a large amount of force be applied to move the grooves 26 into and out of the structure due to the tight engagement. The structure and thus the tooling must be dedicated to that particular type and size of tread 12, which increases the amount of tooling needed for various treads 12, increases the production cost and time necessary to brush. Also, the increased amount of tooling must be changed out when different treads 12 are treated and this change out again increases production time and cost. As such, there remains room for variation and improvement within the art.
Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the invention.